Shoe pad boxes



Dec. 1, 1959 Filed May 8, 1958 F. A. PRAHL, JR., EI'AL snos PAD BOXES 4Sheets-Sheefl Fred ,4 Pmhl, JP; and Era/d 0- Def nse" .9%,?! 7

attorney Dec. 1, 1959 F. A. PRAHL, JR, ETAL 2,91

SHOE PAD BOXES 4 Sheets-Sheet 2 Filed May 8, 1958 V I] as $15 MM WM 1%Dec. 1, 1959 Filed May 8. 1958 F. A. PRAHL, JR., ETI'AL Iaweniom; Fred4. Rnzhl, -77- mi Era/d 0- R v United States Patent srron PAD BOXES FredPrahl, .lr., Harvard, and Evald 0. Peterson, Lynn- 'field, Mass.,assignors to Compo Shoe Machinery Corporation, Waltham, Mass., acorporation of Delaware Application May 8, 1958, Serial No. 733,906

1 Claim. (Cl. 12-38) This invention relates to pad boxes used inwthecementing of shoe soles to shoe uppers.

For use in the cementing of shoe soles to shoe uppers, a widely usedform of pad box has a thin, easily stretchable, soft rubber diaphragmclampe d, with a leather panel, to the pad box, the leather panel beingused to apply pressure to the shoe sole. A problem encountered with thistype of pad box has been that the operating characteristics of the padbox change as the leather panel stretches out. The continued stretchingof the leather panel has caused reductions in the quality of soleattaching, and the continued stretching .of the diaphragm and leatherpanel has caused premature failures of both. Also, with the soft rubberdiaphragm previously used, the unit pressure created on the bottom of ashoe sole has been uniform over the whole bottom surfacev of a shoesole. v

feature of this invention is that it provides'a reinforced, relativelypoorly sretchable, rubber diaphragm which not only eliminates excessivestretching of the diaphragm and its associated leather panel, butenables when the diaphragm is dilated, greatly concentrated pressures tobe applied to the outer portions of a shoe sole.

Another feature of this invention is that a rubber bridge is providedbetween the bottom of the pad box and the diaphragm in its shank area,and a pair of rubber wedges is provided between the diaphragm and theleather panel in the shank area. These cause, when the reinforceddiaphragm is dilated, concentrated pressure to be applied to the outerportions of the shank area of a sole, practically eliminating anypressure on the center portion of the shank area of the sole between itsedges.

An object of this invention is to improve the quality of shoes havingsoles cemented to uppers.

Another object of this invention is to increase the lives of rubberdiaphragms and leather panels used in pad boxes.

Another object of this invention is to limit the stretching of rubberdiaphragms and leather panels used in pad boxes.

Another object of this invention is to increase the pressures applied bythe leather panel of a pad box to the outer portions of an outsole;

This invention will now be described with reference to the annexeddrawings, of which:

i Fig. 1 is a plan view looking downwardly upon a pad box embodying thisinvention;

Fig. 2 is a section along the line 2-2 of Fig. 1, with the diaphragm ofthe pad box not dilated;

Fig. 3 is a plan view of the bottom of the leather. panel of the padbox;

Fig. -4 is a plan view of the top of the rubber diaphragm of the padbox;

Fig. 5 is a section along the line 55 of Fig. 4;

Fig. 6 is a section along the line 6-6 of Fig. 2 with the diaphragm notdilated;

, Fig. 7 is a section along the line 7--7 of Fig. 9, with the diaphragmdilated;

"See

Fig. 8 is a section along the line 88 of Fig. 9, with the diaphragmdilated;

Fig. 9 is a section corresponding to Fig. 2 but with th diaphragmdilated, and

Fig. 10 is an enlarged, fragmentary section through the rubberdiaphragm.

A pad box casing 10 of conventional construction, has clamped thereto bya metal ring 11 and bolts 12, the edge portions of a rubber diaphragm 14and a leather panel 15. A tube 16 for connection to a conventionalsource of compressed air which is not shown, connects through a fitting17 with the space 18 between the bottom of the diaphragm and the casing.A shoe on a last 24, and having an upper 19 and a sole 20, is shown inoperating position on the leather panel '15, being held in such positionby a conventional toe clamp 21 and a conventional heel clamp 22. Theshoe upper has insole lasting margins 23 which are spaced apart underthe last, the usual metal shank piece 29 being placed between thelasting margins.

The bottom of the leather panel 15 has a layer 25 of leatherreinforcement cemented to its fore portion, and has a layer 26 ofleather reinforcement cemented to its heel portion. A steel plate 27 isheld between the heel layer 26 and the bottom of the panel 15.

The diaphragm 14 is reinforced by having two rows of tire cords 28imbedded therein, the cords in one row extending, as shown in thecut-away portion of Fig. 4, at angles of 90 to the cords in theother'row. The cords extend along a bias angle of 45 to the longitudinalaxis of the diaphragm.

i A rubber bridge 30 extends transversely across and is cemented to thebottom of the diaphragm in its shank area. The top of the diaphragm hascemented thereto above the bridge 30, a pair of transverselyspaced-apart, rubber wedges 31 which extend forwardly and rearwardlyabove the bridge 30.

push the panel 15 into the sharp curve of the shoe as shown by Figs. 2and 6. Then, when the diaphragm is dilated, no air pressure is lost inattempting to stretch the leather panel into the contour of the shoebottom. When the diaphragm is dilated by air pressure, the pressureexerted by the leather panel against the surface of the shoe bottom isincreased to the proper operating pressure.. It will be understood that,as is usual in the cementing of shoe soles to shoe uppers, the shoe soleand bottom will have had their adjacent surfaces coated with adhesivebefore being placed in the press, and that'the pad box supplies theproper pressure to hold the insole and outsole together until theadhesive has set.

The reinforced diaphragm and the rubber wedges, as shown by Figs. 7-9,make possible the application of full pressure at the rounded edges ofthe lasting margins 23, with no pressure at the transverse centerportionof the shank where the lasting margins are spaced apart, and

between which is the metal shank piece 29. A transversely rounded shankportion is produced without the necessity of the expensive filling-insteps used in the past to provide the rounded shank portions.

In the shank portion of the shoe where the sole is narrow, and the lastcontours are round, this concentration of force at the edges cannot beaccomplished by using a soft, easily stretchable diaphragm and leatherpanel of the prior art.

In our invention, the top surfaces of the wedges 31 bear against thecemented, marginal edge portion of the shank area of the outsole so thatthe reinforced diaphragm will transfer the accumulated unit pressure onits under surface through the wedges to their upper surfaces, andthrough the latter to the cemented areas of the shank of the outsole, sothat a much higher pressure is developed on the cemented areas of theshank of the outsole than would be possible by a direct pressure fromthe previously used, relatively flexible rubber diaphragm. Not only isthe pressure concentrated in this manner, but dilation of the diaphragmwill cause the wedges to roll up, creating the rounded surfaces desiredby shoemakers, on the shank portion of the shoe. A poorly stretchablediaphragm is required for producing this re sult since the lack ofsubstantial stretchability prevents it from ballooning up alongside ofand between the wedges further than shown by Fig. 8, and causes instead,substantially its full pressure to be applied against the wedges toproduce the desired rounded shank.

In the forepart portion of the shoe, the lack of substantialstretchability of the diaphragm, causes as is shown by Fig. 7,concentrated pressure to be applied to cemented marginal portions of theforepart of the outsole.

The leather panel reinforcement provided by the added layer 25 ofleather in the forepart of the panel, limits the conformation of thepanel to irregularities which may be present in the forepart of the shoebottom. The leather panel reinforcement provided by the added layer 26of leather, and by the metal member 27 prevents the breaking down of thelasted heel.

While a rubber diaphragm is referred to in the description and claim,the word rubber is intended to mean synthetic as well as natural rubberand its equivalents.

What we claim is:

A shoe pad box comprising a casing having a bottom, a rubber diaphragmhaving a substantially ovalshaped outline with its bottom spaced fromsaid casing bottom, a leather panel having an outline similar to saidoutline of said diaphragm overlying said diaphragm and having its edgein contact with the edge of said diaphragm, means for clamping saidedges of said diaphragm and panel to said casing, said panel having ashoe shank contacting portion, a pair of transversely spaced-apart,longitudinally extending, rubber wedges on the top of said diaphragmunder said shank contacting panel portion, a transversely extending,rubber bridge in contact with the bottom of said diaphragm under saidwedges, and means'for supplying air under pressure into the spacebetween said diaphragm and casing bottom.

References Cited in the file of this patent UNITED STATES PATENTS1,725,103 Ray Aug. 20, 1929 1,790,192 Winkley Jan. 27, 1931 2,095,658Card Oct. 12, 1937 2,099,393 Gordon Nov. 16, 1937 2,205,400 Finn June25, 1940 2,311,325 Anderson 2 Feb. 16, 1943 2,348,060 Dawson May 2, 19442,428,814 Russo Oct. 14, 1947 2,733,462 Pratt Feb. 7, 1956 2,772,428Suerken Dec. 4, 1956

